1. Field of the Invention
The present invention relates to a disk module and a disk array apparatus.
2. Description of the Related Art
In general, part of electric power supplied for operating a disk module is converted, for example, into frictional heat due to the rotation of a disk in the disk module and resistance heat of an electronic circuit section. In a disk array apparatus configured of a plurality of the disk modules, amounts of such generated heat become larger as the disk modules are packaged in higher density. Operating characteristics of the disk array apparatus is lowered when the disk array apparatus has a high temperature due to the generated heat. Accordingly, it is necessary to cool the apparatus while the apparatus is being supplied with the electric power.
In a disk array apparatus in recent years, for example, as represented by a large-scale disk array apparatus of a RAID (Redundant Array of Independent Disks) system, a storage capacity thereof has tended to be increased. Specifically, the total number of disk modules included in the disk array apparatus has been increased. Here, if the total number of disk modules is intended to be increased while limiting a footprint of the disk array apparatus to a fixed value, such a disk array apparatus will be highly integrated necessarily.
In general, the disk array apparatus is air-cooled by an exhaust fan provided in a rack accommodating the disk modules therein. In this case, airflows are formed in gaps between the disk modules to remove heat from cabinet surfaces of the disk modules, thus lowering the temperature of the disk modules. Hence, in order to effectively air-cool the disk array apparatus, it is necessary to reduce duct resistance of air by widening the gaps, and thus to strengthen the airflows. This is a condition contradictory to high-density packaging in the disk array apparatus in which the gaps between the disk modules tend to be narrowed.
In order to solve such a contradiction in the above-described condition, for example, a method for enhancing a static pressure of the exhaust fan provided in the disk array apparatus is simple and easy. However, in the exhaust fan, the static pressure has an upper limit (for example, 25 mmAq) in general when the static pressure is enhanced while maintaining stable operation. Hence, the method is insufficient to solve the above-described contradiction.
Meanwhile, a method other than the method for enhancing the static pressure of the exhaust fan has also been adopted. For example, in a conventional disk array apparatus, in an empty space where a disk module is not plugged in, a member in the same shape as that of the disk module is provided. Alternatively, a partition plate for airflow is provided in a space portion between disk modules arranged up and down or arranged facing each other. Thus, the air in the space in the rack is prevented from stagnating, and a decline in airflow strength is controlled. See Japanese Patent Application Laid-Open Publication No. 2001-332078 for example.
However, only with contrivances for such a pseudo module, a partition plate and a draft passage as described above, the disk array apparatus in which the disk modules are packaged in high density cannot be sufficiently cooled. For a disk array apparatus having no empty space for a disk module, the pseudo module does not exert any special cooling effect. Moreover, the contrivances by means of the partition plate and the draft passage cause a necessity of widening the gaps between the disk modules. Hence, these contrivances cannot simultaneously satisfy the contradictory conditions, the high-density packaging in the disk array apparatus and the cooling thereof, while ensuring stable operation.